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4.6 – Noise Draft Environmental Impact Report February 2021 14800 W. Schulte Road Logistics Center 4.6-15 effectively be 0 dBA L eq. Therefore, noise from parking lot activity would be inaudible and would not contribute to the mechanical (HVAC) noise. Truck Loading Dock Activity Noise levels associated with cargo truck delivery activity were also examined in the parking lot study (Baltrënas et al. 2004). The authors of the study concluded that average noise levels from truck loading/unloading areas were 96 dBA at 1 meter (3.28 feet) from the boundary of the truck activity area. Truck loading docks would not be located closer than 1,800 feet from the nearest noise-sensitive land use (a residence). Using the outdoor attenuation rate of 6 dB with each doubling of distance, truck loading activity along the western property bo undary would average 41 dBA Leq. The building configurations would be such that truck loading docks would be interior to the Project site, not facing outward toward noise-sensitive receivers. Substantial acoustical shielding would thus be provided by the approximately 45-foot-high building structures. The resultant loading dock noise at the nearest noise-sensitive land use would be approximately 16 dBA Leq. Similarly, the loading dock noise from the other warehouse buildings would be substantially shielded from the other, more distant receivers to the southwest, east, and west. Consequently, noise generated by truck loading operations would be well below the 50 dBA Leq daytime or the 45 dBA Leq nighttime thresholds set forth by the County. If the loading dock average noise levels were to occur continually throughout a 24-hour day/evening/nighttime cycle, the loading dock noise level would be approximately 23 dBA CNEL at the nearest noise -sensitive land use. The Project would have operational noise levels well below the existing CNEL noise levels based on the traffic noise model results (Table 4.6-7) as well as extrapolating from the short-term ambient noise level measurements (Table 4.6-1). In addition, the operational noise would be well below the existing ambient noise levels in the Project area, and the Project’s contribution to the noise environment would be negligible. Operational noise levels from parking lot activity and HVAC operation (combined) would be well below City of Tracy noise thresholds. Therefore, on-site operational noise levels would be less than significant. Threshold B: Would the Project result in generation of excessive groundborne vibration or groundborne noise levels? Less-Than-Significant Impact. Construction activity may generate vibration that could cause annoyance to people in the Project vicinity and/or have the potential to damage nearby buildings. Construction activities can generate varying degrees of groundborne vibration, depending on the construction procedures and the type of construction equipment operated. Construction equipment generates vibrations that spread through the ground and diminish with distance from the source. The effects on buildings (i.e., building damage) are dependent on the location of the buildings to the source and the characteristic of the building structure. During construction, heavier pieces of construction equipment used at the Project site would include dozers, graders, backhoes, concrete saws, loaders, cranes, loaded trucks, and fork lifts. Groundborne vibration is typically attenuated over short distances. Based on the distance from the construction site boundary to the nearest noise - and vibration-sensitive receptors (a residence located to the northwest) of 1,500 feet, the vibration level is estimated to be approximately 0.0002 PPV inches per second or approximately 34 VdB (FTA 2018), which would be well below the threshold of significance of 0.5 inches per second for building damage; it would also fall well below the FTA’s 75 VdB threshold for potential annoyance. Consequently, temporary vibration impacts from construction would be less than significant.